It’s a neat project, but impractical and kind of dumb for modern hardware.
If you mean it won't implement a lot of functionality which is deviant from the norm, that's probably true, but I expect if it gets popular enough, drivers, patches, dlls, etc will become available.
It also depends on what you want to do with the hardware. I can think of dozens of control applications (SCADA) which don't need today's supermachines, and a simplified assembly based operating system would be great.
It’s practicable. RTOS (real time OS) are used everywhere, particularly in the scientific and industrial computing.